The OAI2LOD Server Exposing OAI-PMH Metadata as Linked Data - PowerPoint PPT Presentation

The OAI2LOD Server Exposing OAI-PMH Metadata as Linked Data

Motivation • more than 1700 institutions worldwide expose metadata via the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) using open standards like URI, HTTP , XML

Motivation • from 900 investigated OAI-PMH repositories • avg. number of Items/Data Provider: ~14,000 1000 843 Number of repositories 100 24 21 10 16 7 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 , , , , , , 0 0 0 0 0 0 2 4 6 8 0 0 - - - - 1 1 1 0 0 0 - > 0 0 0 0 0 0 0 0 , , , 0 0 0 0 , 2 4 6 0 8 Number of items in repository

Goal Fedora @ Library of Inst. Y Congress Austrian DSpace @ DBPedia National Inst. X Library Caltech Bib. Uni. Digital De La Libray Sabana BioMed Central

OAI-PMH at a glance Record 1..* * 1 1 Item MetadataFormat - identifier: URI - metadataPrefix: String 0..* Set - setSpec: String 0..*

OAI-PMH at a glance sample request: http://memory.loc.gov/cgi-bin/oai2_0? verb=GetRecord& identifier=oai:lcoa1.loc.gov:loc.gdc/gcfr.0018_0163& metadataPrefix=oai_dc

OAI-PMH at a glance sample response: <OAI-PMH...> ... <header> <identifier>oai:lcoa1.loc.gov:loc.gdc/gcfr.0018_0163</identifier> <setSpec>ascfrbib</setSpec> </header> <metadata> <dc:title>Don Christopher Columbus to his friend, Don Louis de Santangel</dc:title> <dc:creator>Columbus, Christopher</dc:creator> ... </metadata> </GetRecord>

OAI-PMH at a glance • ListRecords • batch retrieval of records • ListIdentifiers • returns item identifiers • ListSets • returns available sets • Identify

The OAI2LOD Server • makes OAI-PMH resources (items/sets) dereferencable via their URIs • provides metadata access for humans and machines that “do not know” the OAI-PMH protocol • exposes a SPARQL interface to these data • links metadata with other LOD sources

The OAI2LOD Server Linked HTML SPARQL Data Browser Clients Clients HTTP Request Handler / Dispatcher Triple Store Config OAI-PMH & Harvester XSL OAI2LOD Server HTTP OAI-PMH Data Provider

The OAI2LOD Server • LOD Rule 1+2 - “Things should have (resolvable) URIs” • Items: http://example.com/resources/item/ oai:lcoa1.loc.gov:loc.gdc/gcfr.0018_0163 • Sets: http://example.com/resources/set/ ascfrbib • Vocabularies

The OAI2LOD Server • LOD Rule 3: “Deliver useful information when URIs are dereferenced” • Content negotiation based on HTTP Accept • RDF for machines • (X)HTML for humans

The OAI2LOD Server • LOD Rule 4: “Metadata should contain links to other related resources” • link to any other OAI2LOD / LOD data sources • configurable linking property - e.g., rdfs:seeAlso • linking heuristics based on configurable string similarity metrics (e.g., Levensthein, SoundEx)

Outlook • the number of OAI-PMH repositories will grow • major initiatives push its adoption • e.g., “The European Library” • integrates 47 national libraries • provides access to approx. 150 M items

Outlook • OAI-ORE (Object Reuse and Exchange) • latest standardization effort for the “description and exchange of aggregations of Web resources” • data model is based on RDF • concepts have dereferencable URI identifier • aggregations are the means to “link” resources

Further Infos • OAI2LOD - Demos, Download & Instructions: http://www.mediaspaces.info/tools/oai2lod/ • Contact bernhard.haslhofer@univie.ac.at

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BACKUP

Motivation • each OAI-PMH Top 10 Metadata Standards Unqualified Dublin Core 900 compliant repository RFC1807 110 OAI MARC • MUST expose Dublin 108 MARC21 Slim 94 METS Core metadata 69 ETDMS 52 • MAY provide other UK ETD DC 45 MPEG-21 DIDL 41 MetadataFormats ? 39 0 300 600 900